Honours Research
The synthesis & characterisation of core-branched Pt-Ru Nanoparticles
What Are Nanoparticles?
Technically speaking, a nanoparticle is a particle which has at least one of its three dimensions on the nanoscale length. Lengthwise, 1 nanometre is 1 billionth of a metre. So if were were to compare this to everyday objects: if a nanoparticle was the size of a football, then a football would be approximately as big as the earth! Nanoparticles can be all shapes and sizes, from long thin rods, to spheres, cubes and even more complex structures like the ones I made here in my project! And they can be made out of lots of different materials from metals to biomolecules.
Nanoparticles have many applications throughout everyday life! For example titanium or zinc oxide nanoparticles are probably in your sunscreen because they are good at blocking those harmful UV rays from the sun (which can give you sunburn). Another example is in raincoats and other water-proof clothing: when silica nanoparticles are added to the surface of clothing, they can prevent water absorbing into the fabric and instead cause the water to roll off. In medicine, polymeric micelleluar nanoparticles are being used to deliver drugs into the body - by doing this we can prevent the drugs being released into the body too early (e.g. before they reach the target site like the brain or liver).
Finally, in energy, metallic nanoparticles are suspended on carbon bases and used as catalysts in next generation fuel cells and batteries to allow the use of renewable energies (such as hydrogen-fuelled cars). This is where Tara’s research came in: she looked at how we can synthesise nanoparticles with different shapes from two metals (platinum and ruthenium) because platinum-ruthenium nanoparticles are super efficient catalysts in next generation batteries!
Nanoparticle Structure Affects Function
In catalysis, many factors surrounding nanoparticle structure can affect how well the desired reaction works, including:
1. composition (what materials it’s made out of)
2. size (how big or small it is)
3. Atomic arrangement (how the atoms in the nanoparticle are laid out
4. Shape (is it a sphere, a cube, or something else?)
Without getting in to too much detail, Tara knew that platinum and ruthenium were the best materials to use for her reaction, and she knew that the smaller the better (around 8-15nm in size) - this is because the smaller a nanoparticle is, the bigger its surface area, which is where catalysis occurs (so more space = more reactions at once). In order to increase efficiency, she also wanted to try and make complex structures like branched structures because they have increased surface area without using too much excess materials!
One interesting thing to note is that platinum and ruthenium have different preferred atomic arrangements, i.e. under optimal conditions, their atoms will arrange differently in space. Therefore, Tara’s work was looking at how these two metals can build off one another despite having different atomic arrangements!
How Can We Create Nanoparticles With A Specific Structure?
There are two groups of methods we can use to make nanoparticles:
The first type are called “top-down” methods: in these methods we start with larger structures and break them down to make smaller particles - the main drawbacks with these are that we don’t usually have very good control of size and structure. As the particles are broken down we tend to get a wide distribution of sizes (which we don’t want) and we also cannot control shape well which, as we’ve mentioned, is super important in catalytic activity and stability!
Hence, why Tara’s lab group worked with the other type of method called “bottom-up” methods. In these methods, we start with individual atoms and build them up into nanoparticle structures! There are a variety of way to do this, but their group used solution-based syntheses as we can control and tailor a number or reaction variables like temperature, concentration and pressure!
